Amy Winehouse managed to stir up some controversy, even during a relatively smooth set, Saturday night at the Glastonbury Festival in England.

Performing her signature hit "Rehab" while walking along the front row of the audience, Winehouse appeared to punch an unseen fan, judging by a video posted on the BBC News Web site. As she continues singing, Winehouse can be heard grunting as she thrusts a fist into the crowd, then quickly scampers backwards on her high heels under the watch of several large security guards. On continuing her forward progress, she appeared to glare at the person in the spot where the incident took place.

According to the BBC, police said they had received no complaints of assault following the show, and festival organizers said there would be no investigation into the incident. Festival founder Michael Eavis defended Winehouse, saying she appeared to have lashed out at the crowd after being touched by a fan, telling various British media outlets that the audience member had either grabbed the singer's signature beehive hairdo or one of her breasts. It was unclear from the video what provoked the action. But Eavis, describing her set as a "triumph," said that the singer asked if she could headline the fest next year.

During Winehouse's set, the singer also reportedly addressed Kanye West in the midst of performing "Some Unholy War." Festival attendees reported she improvised the lyrics to say, "At least I'm not opening for a c--t like Kanye."

Winehouse and West have no previous bad history, but there has been speculation that the line may be due to the bad publicity West garnered at another festival, the Tennessee-based Bonnaroo Music and Arts Festival. During that show West's set was delayed for hours, raising the ire of fans and media alike. West has since defended himself on his Web site with a passionate rant on his blog. He has already responded to Winehouse's comment with a brief, lighthearted blog headline stating, "This Just In...Amy Winehouse Hates Me!!! Now I've Really Made It!!! LOL!!!!"

Earlier in the week, it was unclear if Winehouse would even be able to make it to the gig at all, following nearly a week of hospitalization for what her handlers said was treatment for pre-emphysema symptoms. But, following a well-received two-song mini set Friday night at a 90th birthday celebration for Nelson Mandela, Winehouse made it to Glastonbury and performed for an hour in front of an estimated 80,000 fans. It was her first full performance in England in seven months, a period during which she canceled nearly all her shows in order to deal with her ongoing health and personal issues.

The night was a bit less rocky for Jay-Z, who took the stage after Winehouse for a set that came pre-packaged with its own controversy. The rapper, the first hip-hop artist to headline the legendary English festival, had been dogged for months ahead of the gig by rumors of disgruntlement over his headlining slot. With his signature swagger intact, Jigga prepped the stage with an introduction that included tape of a BBC interview with Oasis guitarist/singer Noel Gallagher saying that hip-hop was "wrong" for Glastonbury. He then walked on to the strains of Oasis' "Wonderwall" and confronted the audience.

"So they say you guys didn't want to be here tonight," he said, according to the BBC. "They said you guys weren't into hip-hop." The crowd reacted by chanting his name, and Jay thanked them, saying "This is a beautiful moment, I'm glad to share it with each and every one of you."